I had a... well, vision would be a good word as any, about an alternative timeline to Star Wars Galaxy. In this timeline, Mace Windu killed Palpatine. Here's a short story about this:
Even the greatest can fall.
Jedi Master Windu, paragon of the Order, had won. The Sith Lord laid at his feet, under his purple blade. The monster pleaded for his life but Windu knew better than to listen such a creature. Even the young Knight who was with him tried to dissuade him from executing this abomination. But he had to do it. It was the only way. The Master raised his sword, ready to strike when the Force suddenly gave him a warning. Treachery! As he brought the saber down he suddenly changed it's direction and blocked the Knight's blade with it. With his other hand he reached for the Force and electrocuted the treasonous Chancellor. The young Knight however was still redeemable, so Master Windu let him live. It took only a serious talk to see that the Sith had indeed tried to corrupt Skywalker, but he was strong and Windu needed all the good Jedi in the upcoming days.
It was obvious that the Senate had been corrupted. As much as it felt wrong to him, Windu knew that he had to take reins in his hands. So he gathered a group of Knights and marched to the Senate calling an emergency meeting. There he told them what had transpired and that in the interest of Common Good he would take the Republic under his command until the war was over and a new Chancellor could be appointed with proper proceedings.
Convincing the Senate was the easy part. The Council meeting, with those few who were still alive was harder. It seemed that some of the Masters didn't believe in is justification. Indeed, it was apparent that some of them had even fallen to the Dark Side, making weak excuses why he shouldn't take the leadership. It was so obvious that they just wanted to set him aside and take it themselves.
Somehow it all ended with the Council breaking up, both sides exiling the other. The Jedi Order had broken. One part followed Master Windu for the Greater Good. They knew this had to be done for the Republic to survive. One part left with Master Yoda to seek isolation and reform the true Jedi Order. And one part stayed with Master Kenobi to actively oppose Windu's madness.
But the war escalated, and Grand Master Windu had to make hard choices, especially about hunting the renegade fallen Jedi who followed Traitor Kenobi. It became a civil war of Jedi, but it could not be avoided. To stamp out morale issues and dissidence, for the Greater Good, Grand Master had to issue martial law and suppress the freedom of speech. He had to save the Republic.
Two decades later.
The galaxy stands divided. The Confederacy of Allied Systems and the Galactic Republic both hold their grounds. The Order of Pure Jedi does their best to stamp out the Renegade Order who joined the Alliance not long after Grand Master reformed the Order. Both the mighty CAS Droid Army and the infinite Clone Army of the Republic fight an unending war on the frontier space. Grand Master Windu has been forced to hard choices, but everything he has done, has been for the good of the Republic. His greatest asset was Master Skywalker, the strongest Jedi in all history, and was very efficient hunting the Renegades. But the Fallen were numerous and he could not foresee an end to the war any time soon.
The third Order, Yoda's cowards, had hidden themselves and shrouded the Force. They were of no immediate concern to Windu, but he knew he had to deal with them one day. They too had fallen, for fear was the beginning on the road to the Dark Side. And what other reason they could have had to hide, than fear.
The war rages on...